Thich Nhat Hanh calls his practice of yes, "smile yoga." He suggests bringing a slight but real smile to our lips many times throughout the day, whether we are meditating or simply stopping for a red light. "A tiny bud of a smile on the lips," writes Thich Nhat Hanh, "nourishes awareness and calms you miraculously .nbsp;. . your smile will bring happiness to you and to those around you." The power of a smile to open and relax us is confirmed by modern science. The muscles used to make a smile actually send a biochemical message to our nervous system that it is safe to relax the flight, fight or freeze response. A smile is the yes of unconditional friendliness that welcomes experience without fear.
— Tara Brach, Thich Nhat Hanh, Radical Acceptance by Tara Brach